Many of our team are Microsoft Certified Professionals of varying levels, and some members of the consumer technical support team are indeed familiar with Linux variants and are casual users of these types of OS at home, and indeed keeping up-to-date with all relevant and further aspects of IT is always encouraged and essentially a requirement for being able to support an ever changing range of products.
Furthermore, if you were to call today and state that you were using a Linux variant - it wouldn't be a straight off "nope, install Windows" it would in fact be a "under Windows you would need to do X, so we believe that it would be worth looking into how to X under your choice of OS" but sometimes it can be a "XYZ feature only works when you have the Windows driver pack installed, so for that reason it is unlikely that XYZ feature will work on your choice of OS.".
There is a massive difference between having some members of the team being familiar with how to use an operating system, and being able to offer technical advice and troubleshooting for that OS to an acceptable standard for the market - let alone being able to offer a comparable level of support to the much higher standard which we have always offered free for compatible Windows systems manufactured by Novatech.
For those reasons and more, I suspect that if at any point in the future our machines were to become certified for Linux, units installed with that OS would be offered with "hardware only" technical support (which is essentially what is already offered - as explained above).
I hope this helps explain,